Problem: Juan and Rob are selling cookie dough for a school fundraiser. Juan has $t$ cookie dough orders, and Rob has $40$ cookie dough orders. They have a total of $75$ cookie dough orders all together. Write an equation to describe this situation. How many cookie dough orders does Juan have?
Solution: Juan has an unknown number of cookie dough orders, which we're calling ${t}$, and Rob has ${40}$ cookie dough orders. All together, they have ${75}$ cookie dough orders. We can represent Juan and Rob's cookie dough orders as a sum: ${t} + {40}$ We know that together they have ${75}$ cookie dough orders. We can set these two expressions equal to describe this situation with an equation: ${t} + {40} = {75}$ Other ways to represent the situation with an equation include: ${40} + {t} = {75}$ or ${75} = {40} ={t}$, or ${75} - {t} = {40}$. Now we can solve for ${t}$. Subtract ${40}$ from both sides of the equation to get ${t}$ by itself: $\begin{aligned} t +{40} -{40} &= {75}-{40} \\ \\ {t} &={35} \end{aligned}$ The following equation matches this situation: ${t} + {40} = {75}$ Juan has ${35}$ cookie dough orders.